Wednesday, February 18, 2009

Data and stuff for a script test

well, I've been asked for some data to test .. so here is what I've got on this particular small test project I was working on with that 16bit grayscale script:

first off, there are a few programs worth playing with with this sort of data(LIDAR), its been a while but here's what I think I was using to generate/view/translate the original point data that I received..

Depending on how many trees are in your data, you may have to do so other pre-processing on your point data to get as good a bare earth set of points as possible - that's done with another program .. I've been working with some desert point data so I don't have to worry about that with this data set...

quikgrid; to process the bare earth point data into a surfer .grd - This can take a LONG time if you generate a very detailed grid, and you will have to fiddle with settings depending on your point density/trees, so on sparser point data expect to have to regenerate several times before you get a decent .grd - so set aside a weekend and/or work on small segments at a time - I didn't, even though in stage miles this is a very short bit of road, It still took ages for the 20cm and 30cm tests - Patience, and a Fast computer will both do you good:

http://www.perspectiveedge.com/

landserf 2.3 - now you load that .grd so you can generate the shaded releif you will later use as a background in BTB so you can see where to place track and terrain nodes, also take the opportunity to transfer to a format thats easily readable by scripts and other GIS software .. I've been using arc.asc AKA 'ArcGIS text raster' in the landserf save box

now of course is the BTB work, load up that shaded relief as a background, remember your grid corners from quickgrid, and edit the .xml of your BTB save to get the background in the right place..

lay down your track, cross-sections and terrain nodes at appropriate locations on the shaded relief ..

and hope that we can get a script to work!

I would also like such a script to affect surface cross-sections, as this would save much time, cause the generated grids are not perfect, since so much of it is interpolated, it would give a massive head start on the inevitable manual fine tuning.

------------------------------------

Images and data to follow...

First off, here is a 3d view of a grid I generated from LIDAR, this is the data that we are looking at today.

the location is a road just off of a major fault line in California, heading up into the mountains.